RHSA-2008:0389 - Security Advisory

Topic

An updated nss_ldap package that fixes a security issue and several bugs is
now available.

This update has been rated as having low security impact by the Red Hat
Security Response Team.

Description

The nss_ldap package contains the nss_ldap and pam_ldap modules. The
nss_ldap module is a plug-in which allows applications to retrieve
information about users and groups from a directory server. The pam_ldap
module allows PAM-aware applications to use a directory server to verify
user passwords.

A race condition was discovered in nss_ldap which affected certain
applications which make LDAP connections, such as Dovecot. This could cause
nss_ldap to answer a request for information about one user with
information about a different user. (CVE-2007-5794)

In addition, these updated packages fix the following bugs:

• a build error prevented the nss_ldap module from being able to use DNS to

discover the location of a directory server. For example, when the
/etc/nsswitch.conf configuration file was configured to use "ldap", but no
"host" or "uri" option was configured in the /etc/ldap.conf configuration
file, no directory server was contacted, and no results were returned.

• the "port" option in the /etc/ldap.conf configuration file on client

machines was ignored. For example, if a directory server which you were
attempting to use was listening on a non-default port (i.e. not ports 389
or 636), it was only possible to use that directory server by including the
port number in the "uri" option. In this updated package, the "port" option
works as expected.

• pam_ldap failed to change an expired password if it had to follow a

referral to do so, which could occur, for example, when using a slave
directory server in a replicated environment. An error such as the
following occurred after entering a new password: "LDAP password
information update failed: Can't contact LDAP server Insufficient 'write'
privilege to the 'userPassword' attribute"

This has been resolved in this updated package.

• when the "pam_password exop_send_old" password-change method was

configured in the /etc/ldap.conf configuration file, a logic error in the
pam_ldap module caused client machines to attempt to change a user's
password twice. First, the pam_ldap module attempted to change the password
using the "exop" request, and then again using an LDAP modify request.

• on Red Hat Enterprise Linux 5.1, rebuilding nss_ldap-253-5.el5 when the

krb5-*-1.6.1-17.el5 packages were installed failed due to an error such as
the following:

+ /builddir/build/SOURCES/dlopen.sh ./nss_ldap-253/nss_ldap.so
dlopen() of "././nss_ldap-253/nss_ldap.so" failed:
./././nss_ldap-253/nss_ldap.so: undefined symbol: request_key
error: Bad exit status from /var/tmp/rpm-tmp.62652 (%build)

The missing libraries have been added, which resolves this issue.

When recursively enumerating the set of members in a given group, the
module would allocate insufficient space for storing the set of member
names if the group itself contained other groups, thus corrupting the heap.
This update includes a backported fix for this bug.

Users of nss_ldap should upgrade to these updated packages, which contain
backported patches to correct this issue and fix these bugs.

Solution

Before applying this update, make sure that all previously-released
errata relevant to your system have been applied.

This update is available via Red Hat Network. Details on how to use
the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/FAQ_58_10188

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

Fixes

• BZ - 254172 - Automatic DNS discovery of the LDAP server does not work
• BZ - 364501 - pam_ldap tries to change passwords twice
• BZ - 367461 - CVE-2007-5794 nss_ldap randomly replying with wrong user's data
• BZ - 427370 - RHEL 5.1 nss_ldap does not build with RHEL 5.1 krb5 packages

CVEs

• CVE-2007-5794

References

• http://www.redhat.com/security/updates/classification/#low